Infectious diseases are the major cause of morbidity and mortality worldwide. Although many infections cause acute disease, other pathogens, can cause acute and chronic infections. Persistent and latent infections that lead to active disease can be especially difficult to control, particularly because a reservoir of infection exists in the population. Persistent or latent infections are caused by the spectrum of microbes, including viruses, bacteria, parasites, worms and fungi. Diseases caused by persisting pathogens include tuberculosis, schistosomiasis, AIDS, and a variety of herpes-related diseases. The basic requirement of a persistent pathogen is that it evades elimination by the host immune response. Evasion mechanisms of the pathogen complicate strategies for elimination, including vaccine development. However, understanding the strategies employed by microbes for existing in a persistent or latent state can provide clues to potential treatments, vaccines, and immunotherapies that can be developed to control these diseases. In addition, the study of persistent pathogens has contributed to a greater understanding of the immune system. The goal of this Keystone meeting is to bring together scientists with expertise in a variety of persistent pathogens to foster new ideas about control of these pathogens, as well as basic immunologic and microbial concepts. The cross-disciplinary approach will provide an atmosphere amenable to broad thinking and new approaches to studying each pathogen. The unique aspect of this meeting is that it doesn't focus on one class of pathogens, such as viruses alone, but instead spans the entire pathogen world, with the idea that one can learn new strategies from disparate pathogens, and apply findings from one field to research in a different field. This meeting seeks to bring together researchers from a variety of fields, with the common goal of understanding how persistent pathogens survive and how the host responds to such pathogens.